How to Compare Plans With Prescriptions: Formularies, Tiers, and Prior Authorization

When you’re comparing health insurance plans with medications in mind, the sticker price (monthly premium) rarely tells the full story. Your real cost depends on whether your drug is covered, how it’s classified on the plan’s formulary, what tier it falls into, and whether you’ll need prior authorization (or other utilization management steps).

This guide walks you through a consumer-first process for comparing prescription coverage across plans—so you can estimate your true out-of-pocket cost before you enroll. You’ll also learn how to avoid common coverage pitfalls, what to do if a drug is denied, and how pharmacy benefit rules can differ even when two plans look similar.

Why comparing prescriptions is different from comparing premiums

Health insurance premiums are only one piece of your total health costs. For prescription drugs, you also have to account for:

• Deductibles (what you pay before certain benefits kick in)
• Copays and coinsurance (how you pay once coverage starts)
• Drug tier placement on the formulary
• Prior authorization requirements and documentation needs
• Network and pharmacy considerations (including preferred pharmacies)

If you only compare plan premiums and assume your prescriptions are covered, you can end up with “surprise” costs when the plan denies coverage, requires a step you can’t meet, or places your medication on a high-cost tier.

To estimate the full picture, it helps to understand how cost-sharing works in practice. If you haven’t already, review Deductibles vs Copays vs Coinsurance: How to Estimate Your True Out-of-Pocket Cost.

The three pillars of prescription coverage: formulary, tiers, and prior authorization

Most prescription cost comparisons come down to three key concepts.

1) Formulary: the plan’s drug list

A formulary is the official list of covered medications. It can include:

• Generic drugs
• Brand-name drugs
• Preferred brand options
• Specialty medications (often handled differently due to cost and clinical management)

Even within the same insurance carrier, formularies can differ by plan type or benefit design (for example, an HMO versus PPO, or a different plan “year” or “variant”).

2) Tiers: how expensive drugs are for you

Formularies usually assign drugs to tiers, such as:

• Tier 1 (often lowest cost: many generics)
• Tier 2 (commonly preferred brands or certain generics)
• Tier 3–5 (increasing cost, often non-preferred brands or higher-cost categories)
• Specialty tiers (often require additional steps and have high cost-sharing)

Your tier determines how you pay. A medication on a higher tier might be covered, but still cost far more than the same drug—or an alternative—on a lower tier.

3) Prior authorization: plan approval before coverage

Prior authorization (PA) means your plan requires documentation from your prescriber before the medication will be covered at the plan benefit level. In many cases, you must demonstrate you meet certain clinical criteria (or have tried alternative medications first).

Plans may also use other tools closely related to PA, such as:

• Step therapy (try a cheaper drug before the one you want)
• Quantity limits (cap the number of pills per month)
• Age restrictions or diagnosis-based rules
• Formulary edits (like requiring a specific dosage form)

Prior authorization is one of the most common sources of delays, especially during enrollment transitions. If you’re coming from another plan, PA requirements can also change midstream.

Step-by-step: how to compare plans when you take prescriptions

A thorough comparison process takes time—but it’s the best way to avoid enrolling in a plan that looks affordable but fails your medication test.

Step 1: Gather your “drug truth” documentation (before you search)

Before comparing formularies, collect accurate medication details. This prevents mismatches that can cause you to think a drug isn’t covered when the formulary lists it under a different version.

• Medication name (generic and brand)
• Strength (e.g., 20 mg)
• Dosage form (tablet, capsule, injection, etc.)
• Directions (if available—especially relevant for quantity rules)
• Your current prescriber (for PA documentation)
• Monthly supply expectation (30-day vs 90-day)

If you’re dealing with refills, also note your typical pharmacy (or preferred pharmacy chain). While your formulary drives coverage, pharmacy network rules can affect how benefits apply.

Step 2: Identify the right plan year and exact plan variant

Formularies can change by plan year. Don’t rely on last year’s drug list.

When evaluating plan options:

• Confirm the plan year (and that you’re viewing the correct effective date)
• Match the plan name and ID exactly
• Check whether the plan is HMO / PPO / EPO / POS (pharmacy benefit rules can vary)

If you’re enrolling during open enrollment or using a special enrollment period, also confirm the timeline—coverage can delay if enrollment is incomplete.

For enrollment timing and common pitfalls, see Common Enrollment Errors That Trigger Coverage Delays (And How to Prevent Them).

Step 3: Locate the formulary and search each medication by name

Most insurers provide a downloadable formulary list or an online drug search tool. Use both if possible:

• Online tool: quicker for tier and coverage checks
• PDF or downloadable formulary: helps verify details and keep a record

When searching:

• Use generic name first
• Also search brand name
• Try variations (some tools are sensitive to spelling)
• Confirm the formulary entry includes your strength and dosage form

Tip: Screenshot or save the formulary result page for each drug. This becomes useful if you later need an appeal or documentation for prior authorization.

Step 4: Record tier, cost-sharing, and restrictions for each drug

For each medication, you should capture:

• Tier
• Estimated copay/coinsurance structure
• PA required?
• Step therapy required?
• Quantity limit?
• Any special notes (like “must be prescribed by a specialist”)

Even if two plans cover your medication, a higher tier (or stricter requirements) can make the total annual cost dramatically different.

This is where consumers often underestimate value. A plan with a slightly higher premium may be cheaper overall if your drug lands on a lower tier or has fewer restrictions.

To put these costs into context, it also helps to understand the plan’s cost-sharing design. If you want a deeper framework for estimating out-of-pocket expenses, use Deductibles vs Copays vs Coinsurance: How to Estimate Your True Out-of-Pocket Cost.

Step 5: Check whether your drug is on the formulary—but also if it’s “usable” for you

Coverage is not just “is it listed.” It’s:

• Is it on the formulary at all?
• If listed, does it require PA?
• If PA is required, can your prescriber document the criteria?
• If step therapy is required, have you already tried the alternatives?
• Are there quantity limits that don’t match your prescribed use?

A medication may be technically covered but still effectively inaccessible without extra steps.

Step 6: Verify pharmacy network and dispensing rules (especially for expensive drugs)

Many consumers assume drug coverage is universal once you have a plan. But pharmacy benefit rules can include:

• Preferred pharmacy programs
• Mail order availability
• Specialty pharmacy requirements
• Out-of-network pharmacy penalties (depending on plan design)

To avoid surprise bills related to pharmacy and providers, read Network Basics: In-Network vs Out-of-Network and How to Avoid Surprise Bills.

Even if your drug is covered, the wrong pharmacy can lead to higher cost-sharing or rejection.

Step 7: Use a “worst-case / best-case” cost estimate

Because PA and restrictions can affect what you pay and when, it’s smart to model:

• Best-case: Your drug is covered immediately with the expected tier cost
• Worst-case: You face PA delays, step therapy requirements, or higher cost-sharing structures

Include timelines. A delayed approval can force temporary coverage gaps or even out-of-pocket payment while you wait.

For coverage gaps and appeal paths, see How to Fix Coverage Gaps: Retroactive Coverage Options and Appeal Paths.

Understanding formularies: what you’re actually looking at

Formulary documents can be confusing because they combine drug listing with rules. Here’s how to interpret the most common fields.

Common formulary terms (plain-English translation)

• Covered: The plan includes the drug on its formulary
• Tier level: Determines cost-sharing category
• PA: Prior authorization required
• ST or Step therapy: Must try and fail certain alternatives first
• QL or Quantity limit: Caps dose count per time period
• # of days supply: Some plans align authorization to days supply
• Brand/generic substitutions: Some plans allow or require substitutions

When the same drug can be listed multiple ways

You might see multiple entries for:

• Different strengths
• Different dosage forms
• Different product labels (especially for brand drugs)

For example, a plan may cover a generic tablet but exclude a specific extended-release formulation—or cover it only under a specific tier.

Action: Confirm the exact match to your prescription. If you don’t, you risk assuming coverage when the plan’s rules only apply to a different formulation.

Tiers: how to compare prescription cost across plans

Tiers are where consumers can make high-impact mistakes. Two plans can both cover your medication but charge radically different amounts.

Why tier comparisons must be done per drug

You can’t compare tiers at the “plan level” alone. Your medication could be on a:

• Lower tier in Plan A
• Higher tier in Plan B

That difference can overwhelm the premium savings from Plan B in just a couple of fills—especially for maintenance drugs you take monthly.

How specialty tiers often change the economics

Specialty medications usually involve:

• Higher per-month cost-sharing
• Mandatory specialty pharmacy dispensing
• Additional PA requirements

If you’re on a specialty drug, treat the formulary and PA details as the centerpiece of your plan decision.

A consumer-friendly way to compare tiers: build a “drug basket” sheet

For each candidate plan, document your “drug basket”:

• Drug name (generic)
• Tier
• PA requirement (yes/no)
• Estimated copay/coinsurance
• Quantity limit and days supply alignment

Then estimate annual out-of-pocket costs for each plan under both best-case and worst-case scenarios.

This approach works whether you’re enrolling in Marketplace coverage or comparing employer-sponsored plans.

Prior authorization: what it means, why it happens, and how to prepare

Prior authorization isn’t automatically bad—it’s a utilization management step designed to ensure appropriate use. But it can cause delays, especially at enrollment transitions.

What typically triggers prior authorization

Plans commonly require PA for drugs that are:

• High-cost
• Clinically complex
• Often overused or used off-label
• Subject to safety monitoring

Sometimes PA is tied to:

• Diagnosis requirements
• Step therapy history
• Biomarker or lab results
• Age or dosing criteria

How PA affects your cost and timing

PA can impact both:

• Whether you pay the tier copay/coinsurance (if approved)
• How long you go without the medication (if delayed)

Some consumers end up paying out-of-pocket temporarily or missing doses—both of which can be expensive and medically risky.

How to prepare for PA before you enroll

Even if PA is required on the formulary, you can often reduce delays by acting early:

• Call the plan’s pharmacy benefits number and ask what documentation is required
• Ask your prescriber to submit the PA using the plan’s criteria
• Provide your diagnosis and prior medication history if step therapy applies
• Confirm the medication’s exact strength and formulation to prevent denials for “mismatch”

What to do if PA is denied (or never answered)

If PA is denied, most plans provide an appeal process. Your appeal should focus on:

• Medical necessity documentation
• Evidence you meet clinical criteria
• Past treatment failures (if step therapy is involved)

If you’re facing a coverage interruption, review How to Fix Coverage Gaps: Retroactive Coverage Options and Appeal Paths for a structured approach.

Worked examples: comparing two plans for the same prescriptions

Below are realistic scenarios that show why formulary tiers and PA matter more than many people expect.

Example 1: The “covered” drug that still costs far more

Your prescription:

• Brand medication “X” (30-day supply)
• You take it monthly

Plan A:

• Drug is covered at Tier 2
• No prior authorization required
• Copay is stable

Plan B:

• Drug is covered at Tier 4
• Prior authorization required
• Quantity limit aligns with your dosing, but PA adds friction

Even if Plan B has a lower premium, the higher tier cost and PA requirement can outweigh the savings within the first year.

Consumer takeaway: Compare the tier and PA status first, then decide based on premiums second.

Example 2: Step therapy changes the real-world plan choice

Your prescription:

• Medication “Y” for chronic condition

Plan A:

• “Y” is on-formulary at Tier 3 with no step therapy

Plan B:

• “Y” is on-formulary but requires step therapy
• Plan requires trying a lower-cost alternative for a set duration

If you’ve already tried the step-therapy alternatives and have records, PA approval might be straightforward. But if you haven’t, Plan B could cause a treatment delay or require a change in your regimen.

Consumer takeaway: PA isn’t just “required or not.” It can effectively force different treatment paths.

Example 3: Prior authorization causes a refill gap during enrollment

Your prescription:

• Specialty medication “Z” with monthly refills

Plan A:

• “Z” covered, but PA required
• Specialty pharmacy required
• Plan specifies PA submission method and turnaround expectations

Plan B:

• “Z” covered, PA required, and specialty pharmacy required—but Plan B’s specialty network has fewer local options, increasing the time to submit/receive meds

If you enroll late or if your PA paperwork doesn’t follow the plan’s exact process, you could face a refill gap.

Consumer takeaway: Think operationally—how fast approvals happen and how prescriptions will actually be dispensed.

How to compare plans when you take multiple medications

Most people don’t take one drug—they take a basket that includes generics, brands, and possibly specialty meds. That makes comparison more complex, but the method scales.

Build a priority list

Start by ranking your medications:

• Must-continue / high-risk (condition worsens quickly if doses stop)
• Chronic maintenance (stable but important)
• As-needed (lower urgency)
• New or recently changed prescriptions (highest uncertainty for formulary matching)

This helps you focus first on medications most likely to break your health routine if coverage delays occur.

Compare by “coverage continuity risk,” not just cost

Two plans can be similar in estimated cost, but one may have more PA restrictions across your drugs.

When comparing, assess:

• How many of your meds require PA
• Whether step therapy is involved for any “must-continue” meds
• Whether any drugs are not on the formulary at all
• Whether quantity limits could require dose changes

If you want a broader budget framework beyond drugs, you can also align plan choice with metal level strategy using How to Choose a Health Plan Metal Level (Bronze, Silver, Gold, Platinum) for Your Budget.

Metal level won’t replace formulary analysis, but it provides context for premiums and cost-sharing dynamics.

Special considerations for Medicare vs commercial plans (and why it matters for consumers)

Prescription rules can differ depending on whether you’re enrolling in:

• Commercial insurance
• Marketplace plans
• Employer-sponsored coverage
• Medicare (including Part D for prescription drugs)

If you’re in a Medicare context, formulary design still matters, but the benefit structure and processes can be different. Always verify plan-specific PA and formulary rules for the benefit that covers your drugs.

If you’re comparing Medicare options and want a consumer-focused enrollment approach, you may also find value in How to Enroll in Health Insurance: Step-by-Step Guide for Open Enrollment and Special Enrollment, since the “timing and process” issues that cause gaps are similar even when benefit structures differ.

The hidden “gotchas” that cause prescription coverage surprises

Even well-informed consumers can get burned. Here are frequent issues and how to reduce them.

Gotcha 1: The drug is covered, but your exact strength or form isn’t

Formularies can list a medication by generic name, but coverage restrictions apply to specific formulations. A plan might cover the tablet but not your extended-release version.

Fix:

• Confirm the entry matches strength and dosage form.
• Ask your prescriber if a formulary-covered alternative is clinically acceptable.

Gotcha 2: Prior authorization requirements apply only to certain dosages or indications

Some formularies show PA “required” generally. Others show PA for higher doses or particular diagnoses.

Fix:

• Ask the plan what the approval criteria are for your prescribed dosing.
• Prepare diagnosis and prior treatment documentation early.

Gotcha 3: Step therapy is the real barrier

You may assume PA is the problem, but step therapy can block access first. If you haven’t tried the required alternatives, you may be forced to switch treatments.

Fix:

• Document prior medication trials with dates and outcomes.
• If step therapy fails, ask about exceptions and appeal paths.

Gotcha 4: Quantity limits cause month-to-month trouble

If your prescription is for 100 tablets per month but the formulary caps it at 30, you’ll face extra costs or denials.

Fix:

• Confirm the plan’s quantity limit aligns with your prescription.
• Ask your prescriber to adjust the prescription (if clinically appropriate) or submit an authorization for the intended quantity.

Gotcha 5: Pharmacy network issues change what you pay

Some plans have preferred pharmacies that reduce your cost, while out-of-network dispensing can be more expensive or not covered as expected.

Fix:

• Confirm the pharmacy is in-network for the plan’s pharmacy benefit.
• If required, use the plan’s specialty pharmacy for specialty meds.

Network and reimbursement surprises happen in both medical and pharmacy contexts, so keep Network Basics: In-Network vs Out-of-Network and How to Avoid Surprise Bills in mind while you compare.

Using plan documents like a pro: what to request and how to interpret it

If the online formulary search is unclear, don’t stop there. You have the right to request information, and proactive documentation can reduce delays.

Ask these questions (and write down the answers)

When you contact the plan (or pharmacy benefits administrator), ask:

• Is my medication covered under the formulary for my plan?
• What is my medication’s tier?
• Is prior authorization required?
• Is step therapy required?
• Are there quantity limits?
• Which pharmacy types are required (retail, mail order, specialty)?
• Are there any forms or submission methods for PA requests?
• What is the expected timeframe for PA decisions?

Even if you don’t have everything ready, these questions help you understand the operational burden.

Request a written coverage determination when necessary

If you need clarity for urgent medications, ask whether the plan can provide:

• A written explanation of coverage rules
• Guidance for PA submission
• Requirements for exceptions (when appropriate)

For time-sensitive situations, acting quickly matters. If you have a coverage risk, review Common Enrollment Errors That Trigger Coverage Delays (And How to Prevent Them) so you don’t lose critical time to administrative delays.

Planning for costs beyond the prescription price: deductibles, copays, and coinsurance

Your drug copay or coinsurance interacts with the plan’s other cost-sharing mechanics. That’s why two plans with “similar drug tiers” can still result in very different total costs.

How deductibles can affect prescription spending

Depending on plan design:

• Some plans apply drug costs to your deductible first
• Others have specific rules where certain drugs have different cost-sharing pathways

This matters for high-cost medication baskets where you may hit deductible thresholds early or not at all.

For a detailed cost estimation framework, use Deductibles vs Copays vs Coinsurance: How to Estimate Your True Out-of-Pocket Cost.

How coinsurance changes everything for expensive drugs

For specialty medications, coinsurance can be extremely sensitive to the drug’s price and the plan’s negotiated rates. If your medication is subject to coinsurance on a specialty tier, your out-of-pocket can fluctuate more than a fixed copay plan.

Don’t ignore the impact of annual limits and refill timing

Even without explicit annual caps, refill timing can change whether you pay:

• During deductible phases
• During copay phases
• Under PA-approved status

If you’re choosing between plans before open enrollment ends, plan ahead to avoid running out of medication mid-transition.

Practical enrollment workflow for people who rely on prescriptions

Here’s a consumer-friendly workflow that reduces errors and minimizes refill interruptions.

Before you enroll

• Confirm the drug list and tier/PA status for each candidate plan
• Ensure your preferred pharmacies are in-network for pharmacy benefits
• Collect prescriber documentation you can use for PA requests
• Create an action list of what you need to submit (and when)

For consumer process and timing, also reference How to Enroll in Health Insurance: Step-by-Step Guide for Open Enrollment and Special Enrollment.

After you enroll (but before your first refill)

• Confirm your pharmacy benefit details (member ID, group info if applicable)
• Submit PA paperwork if it’s needed and not already in motion
• Ask your prescriber to confirm the prescription matches the formulary entry (strength/form)
• Check that the pharmacy can process your prescription under the plan

If coverage or refills fail due to errors

Coverage gaps can occur due to administrative delays, missing information, or mismatched coverage dates.

For ways to address these issues quickly, use How to Fix Coverage Gaps: Retroactive Coverage Options and Appeal Paths and Common Enrollment Errors That Trigger Coverage Delays (And How to Prevent Them).

How income-related help (premium tax credits) interacts with prescription comparisons

If you’re shopping for Marketplace coverage and may qualify for premium tax credits, it can affect your monthly budget—but it doesn’t replace the need for formulary checks. Premium subsidies reduce what you pay for coverage; they don’t guarantee your prescriptions will be affordable under the drug benefit.

To understand eligibility and calculation mechanics, read Understanding Premium Tax Credits: Eligibility, How They’re Calculated, and What Happens After Filing.

Consumer insight: A plan that feels cheaper due to tax credits can still be more expensive if your medications land on higher tiers or require more PA steps.

Cost-saving strategies that can reduce prescription spending (legally and practically)

Even with careful plan selection, you may still want additional strategies to reduce medication costs.

Explore generics and formulary alternatives (with your prescriber)

If your medication is on a higher tier, your prescriber may be able to use formulary-covered alternatives that are clinically appropriate.

• Ask whether there is a generic version
• Ask whether a preferred brand has equivalent clinical effect for your condition
• Ask whether dosage form changes are feasible without harming outcomes

Use preventive benefits and wellness where relevant

Preventive services don’t replace prescription coverage analysis, but staying current on appropriate care can reduce downstream medication needs. Many plans include preventive care without cost-sharing, depending on coverage design.

If you want a consumer checklist for cutting costs strategically, review Health Insurance Cost-Saving Checklist: HSAs, FSA Rules, and Preventive Care Benefits.

If you’re stuck with a plan that’s expensive: consider exception requests

If a drug you need is excluded or placed on an unusually high tier, you may request:

• A coverage exception
• A tiering exception (rare in some cases but possible depending on plan design)
• An alternative if medically appropriate

Your prescriber can usually provide supporting documentation for exceptions and medical necessity.

A comparison template you can use when shopping (without spreadsheets getting out of control)

You don’t need fancy software to compare plans. A simple structured approach works.

For each plan, capture these fields for every medication

• Drug name + strength + form
• Formulary status: covered / not covered
• Tier: number or label
• PA required: yes/no
• Step therapy: yes/no (and the required alternatives if listed)
• Quantity limits: number and timeframe
• Pharmacy requirements: retail/mail/specialty
• Your expected out-of-pocket: estimated copay/coinsurance

Once you fill that in for all your prescriptions, you’ll be able to rank plans using a scorecard approach:

• Coverage completeness (does the plan cover everything you need?)
• Restriction burden (how many PA/step therapy/QL steps?)
• Estimated cost (annualized out-of-pocket)
• Continuity risk (how likely you’ll face delays at the start of coverage)

This method prevents “premium-only” decision-making.

Common consumer mistakes when comparing prescription coverage

Here are the errors that most frequently lead to enrollment regret.

Mistake 1: You compare only one medication

If you only check the most expensive prescription, you might miss that other meds are not covered—or are on high tiers. A plan should be evaluated as a full drug basket.

Mistake 2: You assume the plan’s formulary is identical year-to-year

Formularies change frequently. Reconfirm every plan for the current plan year.

Mistake 3: You enroll before you confirm PA status for critical meds

If PA is required, the ability to refill promptly matters as much as cost. Waiting until after enrollment can cause gaps.

Mistake 4: You ignore pharmacy dispensing rules

Specialty pharmacies and preferred pharmacy programs can change what you pay and whether you can actually get the medication in time.

Mistake 5: You don’t keep records for appeals

If a denial happens, documentation helps. Save screenshots, plan responses, and written denials.

If you need to understand appeal pathways and how to manage gaps, return to How to Fix Coverage Gaps: Retroactive Coverage Options and Appeal Paths.

How to choose the “best” plan: a consumer scoring approach

Here’s a practical ranking framework that balances cost and access.

Step A: Eliminate any plan that doesn’t cover critical medications

Start with your must-continue meds. If any are not covered—or are effectively inaccessible due to restrictive rules—move to another plan.

Step B: Compare total annual medication cost using tier and PA status

Then estimate:

• Expected copays/coinsurance per month
• Whether deductibles will apply early in the year
• Likelihood of PA delays

Step C: Reduce administrative risk

Plans with fewer PA requirements for your regimen usually win on continuity and convenience. If you’re juggling multiple medications and refills, operational friction is a real cost.

Step D: Confirm pharmacy pathways

Specialty pharmacy and mail order rules can affect whether you can obtain medication quickly. Confirm these before you commit.

Conclusion: prescription-first plan comparison protects your health and your budget

Comparing plans with prescriptions requires more than reading premiums. You need to check the formulary, understand the tiers that determine cost-sharing, and evaluate prior authorization and other restrictions that can delay access.

If you follow the process in this guide—collecting accurate drug details, reviewing formulary entries carefully, documenting tier and PA requirements, and verifying pharmacy dispensing—you’ll be able to choose a plan that fits both your medical needs and your financial reality.

And if something doesn’t go as expected, you’re not stuck: you can use appeal paths, coverage gap strategies, and careful enrollment corrections to recover access and affordability.